﻿<p>A building represents a structure that provides shelter for its occupants or contents and stands in one place. The building is also used to provide a basic element within the spatial structure hierarchy for the components of a building project (together with site, storey, and space).</p>

<blockquote class="extDef">
NOTE&nbsp; Definition from ISO 6707-1:<br>
Construction work that has the provision of shelter for its occupants or contents as one of its main purpose and is normally designed to stand permanently in one place.
</blockquote>

<p>A building is (if specified) associated to a site. A building may span over several connected or disconnected buildings. Therefore building complex provides for a collection of buildings included in a site. A building can also be decomposed in (vertical) parts, where each part defines a building section. This is defined by the composition type attribute of the supertype <em>IfcSpatialStructureElements</em> which is interpreted as follow:</p>

<ul>
 <li><b>COMPLEX</b>: building complex</li>
 <li><b>ELEMENT</b>: building</li>
 <li><b>PARTIAL</b>: building section</li>
</ul>

<p>The <em>IfcBuilding</em> is used to build the spatial structure of a building (that serves as the primary project breakdown and is required to be hierarchical). The spatial structure elements are linked together by using the objectified relationship <em>IfcRelAggregates</em>. Figure 3 shows the <em>IfcBuilding</em> as part of the spatial structure. It also serves as the spatial container for building and other elements.</p>

<blockquote class="note">
NOTE&nbsp; Detailed requirements on mandatory element containment and placement structure relationships are given in view definitions and implementer agreements.
</blockquote>

    <table border="0" cellpadding="2" cellspacing="2" summary=
    "Spatial structure">
      <tr>
        <td valign="top"> <img src="../../../figures/ifcbuilding-spatialstructure.png" alt="IfcBuildingStorey as part of a spatial structure" 
          width="800" height="420" border="0">
        </td>
      </tr>
      <tr>
        <td>
          <p class="figure">Figure 3 &mdash; Building composition
          </p>
        </td>
      </tr>
    </table>
    <p>
      Systems, such as building service or electrical distribution systems, zonal systems, or structural analysis systems,
      relate to <em>IfcBuilding</em> by using the objectified relationship <em>IfcRelServicesBuildings</em>.
    </p>

    <p>
      Figure 4 describes the heights and elevations of the <em>IfcBuilding</em>. It is used to provide the height above
      sea level of the project height datum for this building, that is, the internal height 0.00. The height 0.00 is often used
      as a building internal reference height and equal to the floor finish level of the ground floor.
    </p>
    <ul>
      <li>base elevation of building provided by: <em>IfcBuilding.ElevationOfRefHeight</em>, it is usually the
      top of construction slab
      </li>
      <li>base elevation of terrain at the perimeter of the building provided by: <em>IfcBuilding.ElevationOfTerrain</em>,
      it is usually the minimum elevation is sloped terrain
      </li>
      <li>total height of building, also referred to as ridge height (top of roof structure, e.g the ridge against
      terrain): provided by BaseQuantity with Name="TotalHeight"
      </li>
      <li>eaves height of building (base of roof structure, e.g the eaves against terrain): provided by BaseQuantity with
      Name="EavesHeight"
      </li>
    </ul>
    <table border="0" cellpadding="2" cellspacing="2">
      <tbody>
        <tr valign="top">
          <td align="left" valign="top">
            <img src="../../../figures/ifcbuilding_heights.png" alt=
            "building heights" border="0" height="420" width=
            "800">&nbsp;
          </td>
        </tr>
        <tr>
          <td>
            <p class="figure">Figure 4 &mdash; Building elevations
            </p>
          </td>
        </tr>
      </tbody>
    </table>

<blockquote class="history">HISTORY&nbsp; New entity in IFC1.0.
</blockquote>
